A transceiver is a device including both a transmitter and a receiver that are combined and share common circuitry within a single housing. Optical transceivers are used in a fiber optical transmission system on both transmit and receive sides of a fiber optical link. In systems designed for the access portion of a telecommunications network, optical transceivers typically use single-fiber interfaces (i.e., bi-directional transmission), while for metro and long-haul systems, the optical transceivers typically use dual-fiber interfaces (i.e., one fiber per transmission direction).
Optical transceivers may be fabricated as integrated devices with silicon photonics technologies. The use of silicon photonics can significantly reduce the cost of optics. The cost reduction potential is however strongly depending on the production volumes. Expanding the application range of integrated optical transceivers can increase their volumes of usage and production, and therefore reduce their cost. Current optical transceivers are manufactured for either single-fiber communication or dual-fiber communication, but not both. Therefore, the current optical transceivers have a limited application range and high production cost.
Wavelength-division multiplexing (WDM) is a technology that multiplexes multiple optical carrier signals of different wavelengths onto a single optical fiber to increase capacity. Dense wavelength division multiplexing (DWDM) is one type of WDM that multiplexes optical signals within the 1550 nm band. Today most optical transceivers are used in DWDM metro or long-haul network systems, where dual-fiber communication is performed to prevent transmission impairments. These optical transceivers generally need additional external components (e.g., coupler, filter/mux, circulator, etc.) to work over a bidirectional single fiber. In the near future, DWDM technology will likely migrate further into access networks, where single-fiber communication dominates. Currently, optical transceivers for single-fiber communication are not adapted to the DWDM technology.